It is very important to recycle the waste biomass resources for the environment protection and the circular economy. For this purpose, the waste old loofah was carbonized at 800°C for 1 h in the inert nitrogen gas (N2) atmosphere for lithium ion battery anode. The resultant waste-loofah-derived carbon was investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption and desorption, galvanostatic charge/discharge, cyclic voltammetry and alternating current impedance. The results suggested that the waste-loofah-derived carbon powders consisted of many concomitant microparticles and nanoparticles with a specific surface area of about 492 m2/g. Furthermore, the waste-loofah-derived carbon anode also delivered high electrochemical lithium (Li) storage activity. For example, the initial specific discharge capacity was about 697 mAh/g, and the reversible discharge capacity was about 187 mAh/g at 1000 mA/g for 500 cycles and still about 98 mAh/g even at 3000 mA/g for 500 cycles, exhibiting good cycling stability. High surface area and structural defects may jointly contribute to high electrochemical performances.

Sodium p-toluenesulfonate (TsONa)-doped polypyrrole (PPy) was synthesized as the cathode active material of sodium ion battery by way of facile one-step electrodeposition on iron (Fe) foil. The micro-morphology and micro-structure of assynthesized TsONa/PPy/iron cathode were characterized in terms of scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction; furthermore, the electrochemical Na-storage activity of TsONa/PPy/iron cathode was investigated by methods of, galvanostatic charge/discharge, cyclic voltammetry and alternating current impedance. As expected, the cauliflower-like TsONa-doped PPy particles tightly combined with the surface of the iron foil without any additional polymer binders; and also, the resultant TsONa/PPy/iron cathode delivered satisfactory electrochemical performances, mainly attributed to high Na-storage activity of PPy matrix and high electronic conductivity induced by doping of TsONa. For example, the reversible discharge capacity of TsONa/PPy/iron cathode remained about 98 mAh/g after at least 50 cycles and the corresponding coulombic efficiency was 92%, indicating high cyclic stability and reversibility of TsONa/PPy/iron cathode for sodium ion battery.

As one kind of metal–organic framework material, zinc l-phenylalanine chelate may combine the merits of organic and inorganic components at the molecular level, thus making it a preferred anode active material. However, reports about zinc l-phenylalanine chelate anodes for lithium (Li) ion batteries are still scarce at the moment. Herein, shape-controlled synthesis of zinc l-phenylalanine chelate was carried out through a facile liquid-phase precipitation reaction and subsequent lyophilization. The obtained zinc l-phenylalanine chelate was investigated by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, galvanostatic charge/discharge and cyclic voltammetry. The results suggest that zinc l-phenylalanine chelate appeared as uniform nanofibers about 140 nm diameter and 2–5 μm long. Furthermore, the zinc l-phenylalanine chelate nanofiber anode exhibited satisfactory electrochemical performances. For example, the initial specific discharge capacity was as high as 255 mAh/g at 100 mA/g and the reversible capacity remained 109 mAh/g even at 1000 mA/g for 200 cycles. Additionally, the possible lithium-storage mechanism was also explored. The synergistic effect of the combination of organic/inorganic components at the molecular level, regular nanofiber-like morphology and structural cavities may facilitate good strain accommodation, short ionic/electronic transport paths and high electrochemical performance.

As one common industrial waste liquid, waste copper (Cu) etchant can seriously pollute the environment if it is unreasonably managed. Herein, tetrahedron-like copper (I) chloride (CuCl) crystals were extracted from waste copper etchant by way of facile electrodeposition, and the effect of the electrodeposition time on the lithium (Li)-storage capacity of the copper (I) chloride crystal was further investigated. The results showed that the copper (I) chloride crystal had a regular tetrahedral morphology, and the density of the regular tetrahedral particles gradually increased with the extension of the electrodeposition time from 5 to 15, 20 and 25 s. Correspondingly, the reversible lithium-storage capacity of the copper (I) chloride anode experienced an initial increase and a subsequent decrease. In detail, when cycling at 2 C for 250 cycles, the reversible discharge capacity of the copper (I) chloride anode increased from 187·3 mAh/g at 5 s to 284·5 mAh/g at 15 s and then decreased to 191·9 mAh/g at 20 s and to 125·3 mAh/g at 25 s, indicating that 15 s may be the most optimal electrodeposition time. Excessive copper (I) chloride particles may result in poor performance due to the poor inherent conductivity of copper (I) chloride. Such efforts would alleviate environmental pollution and facilitate the circular economy of wastes.

The wide application and oversupply of various medicines are inevitably accompanied by the production of massive amounts of expired medicines, which can trigger the environmental contamination and waste of resources if these are not reasonably managed. For this reason, the efforts were made to recycle two expired medicines (lithium carbonate (Li2CO3) and ferrous sulfate (FeSO4) tablets) simultaneously into magnesium ion-doped lithium iron phosphate (LiFePO4; LFP)/carbon (C) powders through a facile high-temperature solid-state reaction. In addition, the economic feasibility was analyzed and discussed. The results suggested that 0·51 wt% magnesium ions were successfully doped into the lithium (Li) site of LFP/carbon, and the corresponding molecular formula was Li0·92Mg0·04FePO4/C, which resulted in the double effects: a decrease in the unit cell volume and an increase in the electronic conductivity. Furthermore, the magnesium ion/LFP/carbon cathode also exhibited better electrochemical lithium-storage performance compared with the undoped LFP/carbon cathode, indicating high application feasibility in lithium-ion batteries. Additionally, the recycling process was economically profitable, which would stimulate the development of the circular economy of waste expired medicines and lithium-ion batteries.